<template>
  <div class="p-code">
    <canvas id="p-code" :width="contentWidth" :height="contentHeight"></canvas>
  </div>
</template>

<script>
export default {
  props: {
    identifyCode: {
      // 默认注册码
      type: String,
      default: '1234'
    },
    fontSizeMin: {
      // 字体最小值
      type: Number,
      default: 25
    },
    fontSizeMax: {
      // 字体最大值
      type: Number,
      default: 35
    },
    backgroundColorMin: {
      // 验证码图片背景色最小值
      type: Number,
      default: 200
    },
    backgroundColorMax: {
      // 验证码图片背景色最大值
      type: Number,
      default: 220
    },
    dotColorMin: {
      // 背景干扰点最小值
      type: Number,
      default: 60
    },
    dotColorMax: {
      // 背景干扰点最大值
      type: Number,
      default: 120
    },
    contentWidth: {
      // 容器宽度
      type: Number,
      default: 90
    },
    contentHeight: {
      // 容器高度
      type: Number,
      default: 38
    }
  },
  watch: {
    identifyCode() {
      this.drawPic()
    }
  },
  mounted() {
    this.drawPic()
  },
  methods: {
    // 生成一个随机数
    randomNum(min, max) {
      return Math.floor(Math.random() * (max - min) + min)
    },
    // 生成一个随机的颜色
    randomColor(min, max) {
      let r = this.randomNum(min, max)
      let g = this.randomNum(min, max)
      let b = this.randomNum(min, max)
      return 'rgb(' + r + ',' + g + ',' + b + ')'
    },
    //画图
    drawPic() {
      let canvas = document.getElementById('p-code')
      //创建一个2D对象作为上下文。
      let ctx = canvas.getContext('2d')
      ctx.textBaseline = 'bottom'
      // 绘制背景
      ctx.fillStyle = '#e6ecfd'
      ctx.fillRect(0, 0, this.contentWidth, this.contentHeight)
      // 绘制文字
      for (let i = 0; i < this.identifyCode.length; i++) {
        this.drawText(ctx, this.identifyCode[i], i)
      }
      this.drawLine(ctx)
      this.drawDot(ctx)
    },
    //在画布上显示数据
    drawText(ctx, txt, i) {
      ctx.fillStyle = this.randomColor(50, 160) // 随机生成字体颜色
      ctx.font =
        this.randomNum(this.fontSizeMin, this.fontSizeMax) + 'px SimHei' // 随机生成字体大小
      let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1))
      let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5)
      var deg = this.randomNum(-30, 30)
      // 修改坐标原点和旋转角度
      ctx.translate(x, y)
      ctx.rotate((deg * Math.PI) / 180)
      ctx.fillText(txt, 0, 0)
      // 恢复坐标原点和旋转角度
      ctx.rotate((-deg * Math.PI) / 180)
      ctx.translate(-x, -y)
    },
    // 绘制干扰线
    drawLine(ctx) {
      for (let i = 0; i < 4; i++) {
        ctx.strokeStyle = this.randomColor(100, 200)
        ctx.beginPath()
        ctx.moveTo(
          this.randomNum(0, this.contentWidth),
          this.randomNum(0, this.contentHeight)
        )
        ctx.lineTo(
          this.randomNum(0, this.contentWidth),
          this.randomNum(0, this.contentHeight)
        )
        ctx.stroke()
      }
    },
    // 绘制干扰点
    drawDot(ctx) {
      for (let i = 0; i < 30; i++) {
        ctx.fillStyle = this.randomColor(0, 255)
        ctx.beginPath()
        ctx.arc(
          this.randomNum(0, this.contentWidth),
          this.randomNum(0, this.contentHeight),
          1,
          0,
          2 * Math.PI
        )
        ctx.fill()
      }
    }
  }
}
</script>

<style lang="less" scoped></style>
